FeCl3⋅6H2O-catalyzed intermolecular-cascade cyclization of acetoacetanilide: aldehyde-tuned synthesis to valuable 2-pyridone analogues

The first ever breakthrough toward activation of β-ketoacetanilide and subsequent C-C and C-N bond-forming intermolecular-cascade cyclization processes is demonstrated by development of the unprecedented Lewis acid property of non-toxic FeCl(3)?6H(2)O. Aromatic, aliphatic, α,β-unsaturated, chiral sugar-based and chromone aldehydes were regio- and stereoselectively cyclized with acetoacetanilides toward construction of valuable N-containing highly functionalized 2-pyridones (see scheme for an example).     

Energy transfer induced enhancement of localized exciton emission in ZnO nanoparticle–anthracene hybrid films

Optically transparent and high‐quality hybrid ZnO nanoparticle and anthracene embedded polyphenylsiloxane (PPS) glass films were spin‐coated on quartz substrates. A strong Förster resonant energy transfer (FRET) process was indicated by the observation of quenching of the ZnO emission and an enhancement of the anthracene emission at room temperature. The efficiency of this energy transfer between ZnO and the S₁ vibronic states of the anthracene molecules can be optimized to exceed 90%.

     

Solvation energy of multiply charged anions and dielectric constant for finite system: a microscopic theory based bottom-up and top-down approach

This is the first time a microscopic theory-based bottom-up approach has been implemented to derive an analytical expression for the solvation energy for a finite (N) system, including the bulk. This bottom-up approach provides the information on solvation energies of anionic solutes in finite-size clusters, including the bulk (N = ∞), from the knowledge of the detachment energies for the system containing a few numbers of solvent molecules. However, in the case of dielectric constant, a microscopic theory-based top-down approach has been prescribed to derive an analytical expression for the static dielectric constant for the finite system. In this approach, the knowledge of the dielectric constant for the bulk provides a scheme to obtain the same quantity for a wide numbers of solvent molecules. As an illustrative example, the hydrated doubly charged anions, SO^?2 ₄.NH₂O and C₂O^?2 ₄.NH₂O, have been considered, and the calculated bulk solvation energy for the SO^?2 ₄.NH₂O system is found to be in very good agreement (within 5%) with the available experimental result. However, the same quantity calculated based on the Born model is found to be largely deviating (32%) from the experimental result. The calculated results of the dielectric constant for these two systems support the linear theory of dielectric constant.     

Mechanistic and kinetics study of the gas phase reactions of methyltrifluoroacetate with OH radical and Cl atom

Theoretical investigations are carried out on the title reactions by means of ab initio and DFT methods. The optimized geometries, frequencies and minimum energy path are obtained at MPWB1K/6-31+G(d,p) level. Single point energy calculations are performed at MP2 and QCISD(T) levels of theory. Energetics were further refined by calculating the energy of the species with a high level G2(MP2) method. The rate constant of the two reactions are calculated at 298?K and 1?atm using Canonical Transition State Theory (CTST) utilizing the ab initio data obtained during the present study. The rate constant values are found to be 5.5?×?10^?14 and 5.9?×?10^?14?cm³ molecule^?1 s^?1, respectively which are in good agreement with the experimental data.     

Highly efficient one-pot, three-component Mannich reaction catalysed by boric acid and glycerol in water with major ‘syn’ diastereoselectivity

Boric acid and glycerol efficiently catalysed the one-pot, three-component Mannich reaction of aldehydes, aromatic amines and cyclic ketones in water at ambient temperature to afford the corresponding β-amino carbonyl compounds in good yields. All but one reaction proceeded with moderate ‘syn’ diastereoselectivity. This observation is just the reverse of the major anti diastereoselectivity obtained in most of the earlier reported procedures. The methodology is mild and efficient using minute quantities of catalyst with no side products and a very simple work-up procedure.     

Dimension Asymptotics for Generalised Bootstrap in Linear Regression

We prove consistency of a class of generalised bootstrap techniques for the distribution of the least squares parameter estimator in linear regression, when the number of parameters tend to infinity with data size and the regressors are random. We show that best results are obtainable with resampling techniques that have not been considered earlier in the literature.     

Estimating the asymptotic dispersion of theL 1 median

A simple estimate of the asymptotic dispersion matrix of theL ₁ median is proposed and its rate of convergence is studied.Research supported in part by a grant of the Indian Statistical Institute.